Rat trophoblastic cell antigenicity.

Trophoblast cells were isolated from the trophoblast giant cell (TGC) layer associated with the rat parietal yolk sac and from the chorioplacenta. Antisera to these cells were produced in the rabbit and analysed with several test systems. Anti-TGC sera reacted with Reichert's membrane (RM), TGC, and chorioplacental trophoblast cells (CTC) by immunodiffusion, and immunofluorescent localization showed that antisera produced against both preparations of trophoblast cells reacted with antigens present in RM and the maternal and renal glomeruli. There was no localization in the trophoblast cells themselves. The abortifacient effects of trophoblastic antisera, which were previously reported, were not found to be due to antisera produced to specific antigens of the trophoblastic preparations which were utilized. In fact the only abortigenic effect observed could be eliminated if the TGC antisera were absorbed with RM. There are several possibilities to explain the presence of antigens in the TGC and CTC which cross-react with RM, and these are discussed, but it is important to recognize that, in the rat, the preparations of antisera to TGC and CTC may produce abortigenic and embryotoxic effects by their actions not on the chorioplacenta, but on the yolk sac placentae. Both the previous reports of embryotoxicity of trophoblastic antisera and our own findings only raise many new questions that have obviously not been answered by this study. But these studies make it quite apparent that any immunological, embryotoxic or teratological studies in the rodent that deal with antigens of the chorioplacenta must include simultaneous immunological and biological studies involving the yolk sac placentae, since dysfunction in either of these placentae can result in various types of reproductive failure.